ISOLATION AND CHARACTERIZATION OF 2 NOVEL GENES EXPRESSED IN GERMINATING CONIDIA OF THE OBLIGATE BIOTROPH ERYSIPHE-GRAMINIS F SP HORDEI

A cDNA library was constructed from germinating conidia of the obligat e biotrophic fungus, Erysiphe graminis DC ex Merat f.sp. hordei Em, Ma rchal (Egh). Subtractive hybridization and differential screening were carried out. Two cDNA clones, cEgh7 and cEgh16, which were highly exp ressed in germinating conidia, but not in ungerminated conidia, were s elected for further characterization. The corresponding genomic sequen ces, gEgh7 and gEgh16, were isolated from a cosmid library and sequenc ed. The gEgh7 gene contains an open reading frame (ORF) that codes for a 249-amino-acid (aa), Pro-rich polypeptide with a repeated primary s tructure. Expression studies in planta indicated that gEgh7 may have a function in the development and maturation of conidia. The ORF of gEg h16 is interrupted by two introns of 91 and 119 bp. It encodes a 251-a a polypeptide of unknown function. This gene belongs to a multigene fa mily and is expressed during all developmental stages of Egh in planta and may be associated with hyphal growth.